One objective is to determine the lateral mobilities and lateral distributions of membrane-bound haptens in reconstituted lipid model membranes of defined composition, using techniques of spin-label paramagnetic resonance, nuclear magnetic resonance, and freeze-fracture electron microscopy. Haptens of special interest are those that contain the paramagnetic spin label group as the haptenic moiety. A second objective is to determine whether or not there exists a causal, quantitative and understandable relation between the lateral distributions, their lateral mobilities and (a) the susceptibility of hapten-sensitized lipid vesicles to complement-mediated, and to lymphocyte-mediated, antibody-dependent attack, and (b) the degree to which such vesicles can elicit an immune response in vivo and in vitro. A third objective involves a collaborative study with Dr. J. Kriss and his associates in the Radiology Department of Stanford Medical School; this objective is concerned with the preparation and study of small lipid vesicles that ideally have physical, chemical and immunological properties that render them potential tools for cancer detection, chemotherapy, immunotherapy, and radiotherapy.